Shading devices and daylight quality: An evaluation based on simple performance indicators

The impact of seven shading devices on daylight quality in a south-oriented office was investigated by simulations with Radiance at three specific times on three sunny days. Daylight quality was assessed for a large number of desk positions by considering simple performance indicators: the absolute and relative work plane illuminance and the absolute and relative luminance of surfaces. The results indicated that the white awning, overhang and horizontal venetian blind provided adequate work plane illuminances for traditional office tasks but yielded high window luminances. The 45° venetian blind, white screen and blue awning provided suitable work plane illuminance for computer work and acceptable luminance ratios between the VDT, work plane and surroundings. The grey screen yielded unacceptably low illuminances and luminances, poor uniformity and unacceptable luminance ratios.